Gmod and TF2 (hl2.exe) problems

Where should i start? Okay maybe from when my gmod was working but it started to have problems. First i have played gmod for like 700+ hours on steam, bought it two years ago. and this summer i accidentally set my resolution too high, and i could not play the game because of the lag. When i started the game it opened, but when i got to the homescreen the game froze, and my computer became unresponsive aswell, i could not even ent the task, because my computer froze. Only way to close it was to force restart the computer. So i had that problem for 3 days, and was triying to figure stuff out, but then i went away for two weeks, and when i got back, and tried opening gmod, the window appeared saying “Preparing to launch Garry’s Mod” and when it went away nothing happened, i waited an hour, but still nothing, and my computer did not freeze, so when i wanted to play another game, it said that gmod is running, but it was not open, so i closed it in the task mananger. The same problem is with my TF2. I have tried everything, deleting clientregistry.blob, then uninstalling the game, verifiying the integrity of game cache, -autoconfig, EVERYTHING even flushconfig steam. Nothing has worked yet! Please help me.
The problem is on my pc, but the game works perfectly on my mac (only crashes every 60 mins). Please help me.

Try adding this to your launch options: -w 800 -h 600